<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<button id="btn03">click me~</button>
		<script>
			let btn03 = document.getElementById('btn03')
			btn03.addEventListener('click', () => { //不会被覆盖
				console.log('first');
			})
			btn03.addEventListener('click', () => {
				console.log('second');
			})
		</script>
	</body>
</html>
